The ecosystem of the Yellow River Delta is at risk of salinization. Plant litter is an environmentally friendly and readily available improvement material. However, after the addition of litter, the changes in enzyme activity and carbon components of saline-alkali soil and their interrelationships have not been fully understood. This study used culture experiments to analyze changes in soil enzyme activities and carbon components following the addition of two plant litters ( Medicago sativa, Sorghum dochna). The results showed that within 30 days of cultivation, soil enzyme activities (β-glucosidase, urease, alkaline phosphatase, dehydrogenase) and labile carbon (DOC, MBC, POC) rose compared to the control. However, enzyme activities and labile carbon dipped by 80 days. Mineral-associated organic carbon (MAOC) remained non-significant change. There was strong positive links between DOC, MBC, POC and enzyme activities, highlighting labile carbon’s key role in driving microbial and enzymatic processes. Furtheremore, litter addition enhanced soil quality. This study showed short-term plant litter addition boosts soil enzyme activity and labile carbon in saline-alkali soils. But these gains aren’t long-lived, highlighting the need for ongoing organic inputs. Plant litters are eco-friendly, practical short-term soil amendments. For lasting soil fertility and resilience in saline-alkali ecosystems, long-term strategies blending organic inputs and microbial management are crucial.